CVE-2026-98173

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix use-after-free of iface in cifs_try_adding_channels() cifs_try_adding_channels() iterates ses->iface_list with list_for_each_entry_safe_from(), which captures the next entry (niface) under iface_lock. The loop body then drops iface_lock for the whole duration of cifs_ses_add_channel(). A concurrent interface refresh (SMB3_request_interfaces() -> parse_server_interfaces()) marks all ifaces inactive and removes and frees any that are not re-advertised via list_del() + kref_put(), where release_iface() is a bare kfree(). Since niface typically has no channel holding a reference, the list reference is its last and it can be freed inside the unlocked window. On continue, the iterator advance step then dereferences niface->iface_head.next, and the loop body reads iface->rdma_capable/is_active, both on freed memory. Fix this by never keeping an unreferenced list pointer across the unlocked window. Each channel attempt now re-scans the list from the head under iface_lock, takes a kref on the selected candidate, and passes only that referenced candidate to cifs_ses_add_channel(). weight_fulfilled still tracks selection progress, so restarting the scan preserves the original weighted distribution and the weight_fulfilled-before-kref_put ordering on the failure path. Add a per-pass attempts cap so a flapping interface refresh cannot keep the inner loop spinning within a single tries increment.

Is your site exposed to CVE-2026-98173?

Run a free security scan — no signup, results in seconds.

EPSS — Exploit Prediction

0.0021

Probability of exploitation

0.10%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

References

Other References

https://git.kernel.org/stable/c/c941f1ebfd26f683de81091473f3596a218abff0 https://git.kernel.org/stable/c/d034e836eefd7ce75e588f7031cffbeec594f5ac https://git.kernel.org/stable/c/e99040e5e9c60441e6b4725e1a7b88c3106ae903 https://git.kernel.org/stable/c/ec36b38e65596950e6c29bed7dfc90b98707c19c

Frequently Asked Questions

What is CVE-2026-98173? +

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix use-after-free of iface in cifs_try_adding_channels() cifs_try_adding_channels() iterates ses->iface_list with list_for_each_entry_safe_from(), which captures the next entry (niface) under iface_lock. The loop body then drops iface_lock for the whole duration of cifs_ses_add_channel(). A concurrent interface refresh (SMB3_request_interfaces() -> parse_server_interfaces()) marks all ifaces inactive and removes and frees any that are not re-advertised via list_del() + kref_put(), where release_iface() is a bare kfree(). Since niface typically has no channel holding a reference, the list reference is its last and it can be freed inside the unlocked window. On continue, the iterator advance step then dereferences niface->iface_head.next, and the loop body reads iface->rdma_capable/is_active, both on freed memory. Fix this by never keeping an unreferenced list pointer across the unlocked window. Each channel attempt now re-scans the list from the head under iface_lock, takes a kref on the selected candidate, and passes only that referenced candidate to cifs_ses_add_channel(). weight_fulfilled still tracks selection progress, so restarting the scan preserves the original weighted distribution and the weight_fulfilled-before-kref_put ordering on the failure path. Add a per-pass attempts cap so a flapping interface refresh cannot keep the inner loop spinning within a single tries increment.

How do I check if I'm vulnerable to CVE-2026-98173? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.